Oil-immersed vacuum-type switch



April 21, 1931. TIT. GREENWOOD OIL IMMERSED VACUUM TYPE SWITCH Filed 001 so, 1926 2 Sheets-Sheet 1 llllll I 3 q 551% 0 s m m I 7 6 MW 32 W H a I 5 P w m m I April 21, 1931. T. T. GREENW OOD 1,801,736

OIL IMMERSED VACUUM TYPE SWITCH Filed Oct. so, 1926 2 Sheets-Sheet 2 able switch member.

Patented Apr. 21, 1931 UNITED STATES PATENT OFFICE TALMA T. GREENWOOD, OF EAST TEMPLETON, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL MANUFACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS,

A CORPORATION OF MASSACHUSETTS OIL-IMMERSED VACUUM-TYPE SWITCH Application filed October 30, 1926. Serial No. 145,326.

This invention relates to circuit interrupters of the type wherein the circuit interrupting arc is'dra-wn. in a high vacuum and preferably between separable contact members from which the occluded gases have been removed.

The vacuum type switch comprises an evacuated container composed usually of some insulating material as glass. Stationary and movable contact members are disposed within the container and the stationary contact members are led out of the container through suitable seals.

Due to the fact that it is imperative that a high vacuum be maintained within the container, the movable contact member can not be brought out through the wall of the container for connection with externally-disposed switch operating mechanism since air will leak into the container through any common form of packing that may be utilized between the container wall and the mov- It has consequently been necessary to enclose the movable switch member entirely within the container and provide it with a magnetizable member and to operate it by electro-magnetic means disposed externally of the container. Such an arrangement is undesirable since it places the electro-magnetic operating means relatively near the high tension circuit leads and invites a flash-over therebetween and also be cause it limits the switch to electro-magnetic operation which is not desirable for many purposes.

An object of this invention therefor is the'provision of a vacuum type switch wherein the container is permanently sealed against air leakage thereinto and is provided with means whereby the movable switch member can be operated mechanically by movable means disposed externally of the container.

A further object of the invention is the provision of a vacuum type switch with a permanently sealed container having a flexible wall to one side of which wall, the movable switch member is operatively connected and I to' th e other side ofwhich wall theoperating' t9 mechanism is-.:- operatively connected, the

operated by the flexing of the Fig. 1 is a vertical sectional elevation through the circuit interrupter embodying the invention.

Fig. 2 is a sectional detail showing one of the vacuum switches of Fig. 1 in open circuit position.

Fig. 3 is a section along line 33 of Fi 1.

Fig. 4 is a sectional view similar to ig. 2 but showing a modified arrangement wherein external pressure acting on the flexible wall serves to bias the switch for opening movement.

The circuit interrupter here shown as embodying the invention comprises an enclosing casing including the receptacle 1() and the detachable cover 12. Said cover and receptacle are adapted to be secured removably together in a fluid tight manner. The entire casing is preferably, although not necessarily, completely filled with an insulating fluid as oil whereby to exclude the atmosphere from direct contact with the body of oil in the easing and thereby to prevent auto-oxidation and deterioration of the oil. A slight head or pressure of oil may be maintained in the casing by the provision of the oil storage tank 16 which is adapted to contain a supply of oil therein to some level that is above the top of the casing. The body of oil within said tank is in communication with the body of oil in the casing by means of the pipe 18.

The tank 16 may be vented to the atmos-- The circuit interrupter is provided witha pair of terminals 22 which are extended through insulators 24 rigidly carried by the cover 12 and extended therethrough into the interior of the casing. The lower ends of said terminals "are connected electrically with the vacuum switch comprising a part of this invention and also serve as the mechanical support for the casings of said switch.

through the Ihe vacuum switch forming part of this invention comprises essentially two separate switches electrically connected in seriesand adapted conjointly to control the circuit interrupter. The vacuum switches are or may be identical in'construction. Each switch comprises a generally cylindrical container 26 composed preferably although not necessarily of some suitable insulating material as glass. The container dis osed within said container 26.

is formedwith reduced open necks 28 and 29 at its upper and lower ends respectively. A metal cap 30 is welded on the upper end 28, thereby sealing said'neck. Said cap is provided with an externally-disposed screwthreaded stud 31 which is passed throughthe leg 32 of a conducting supporting member 34.

cap 44 is sealed on welded to the lower neck 29. Said ca cisprovided with an outstanding annular ange 46 to which is welded or otherwise secured-in vacuum tight manner one end of a flexible wall member 48. Said wall member is of general tubular form and has its side wall corrugated as indicated at 50. The side wall is of relatively thin and flexible metal and the corrugations there- 7 in are relatively deep and so arranged that .ed in Fig. 1. Y

the member may be elongated in an axial direction as indicated in Fig. 2, and it may also be compressed into the position illustrat- The bottom end of said flexible wall member is sealed or welded to a bottom plate 52. The movable switchmember comprises a rod 54 which as here shown is fixed rigidly to the inner face of said bottom plate. 52 and extends within the container 26 in the line of said stationary contact member 42 and is adapted "to be moved into and out of said contact member u on the flexing of said wall member 48. The exible wall member is adap ed to beexpanded andcontracted by ext nallydislplosed means acting thereon. The flexible member thereby provides means whereby motion may be transferred to the interior Said connector 34'is rovided with'an of said evacuated container 26 from externally-disposed actuating mechanism while maintaining the seal of said container.

The bottom plates 52 of both containers are attached to a rigid conducting bar 56' which serves electrically to connect the movable contact members of the two containers and also to actuate both switches conjoint ly. An insulating switch operating rod 58 is attached to said bar 56 and is extended upwardly in the space between the two containers and through the neck 60 of the cover 12 for attachment to suitable operating mechanism disposed externally of said casing. The upper end of said neck 60 is terminated above the level of the oil in the tank 16 to prevent escape of oil from the casing. It is apparent that as said rod 58 is moved downwardly, the flexible walls 48 will be elongated into some position as illustrated in Fig. 2, thereby separating the stationary and movable'contact members and interrupting the circuit through the interrupter.

Atmospheric pressure operating on the flexible walls 48 through the medium of the body of oil contained in the interrupter casing tends to collapse or compress said flex ible walls when the restraint on the switch rod 58 is removed, thereby to eflect the closin of the interrupter.

or some purposes, it may be desirable to have the interrupter biased for switch opening movement. Such a construction is illustrated in Fig. 4 wherein the movable con tact member 54 a is pivoted to and carried by parallel levers 62. Said levers arepivoted to an ear 64 carried by the flange 46m. A link 66 is pivotally connected with the free ends of said levers and with the bottom plate 52a.' As thus arranged, the upward'movement of the bottom plate, due either to the operation of the switch rod 58 or to atmospheric pressure exerted thereon, effects the opening of the switch. i The containers 26 are adapted t be evacuated toas high a degree as practic ble. The parts in communication with the interior of said containers, and especially the separable contact members, are adapted to have the occluded gases removed therefrom. A rela- I tlvely large amount of energy can thus be interruptedwith a small circuit interruptingarc and the circuit interrupting arc will be rapidly extinguished. The construction may be otherwise modified without departing from the spirit of the invention.

The broad idea of a vacuum switch having a flexible wall through which motion of the external switch operating mechanism .is transferred to the internal separable contact members is disclosed and claimed in my concurrently filedapplication Serial No. 145,328.

Iclaim':

supported insulated terminal, an evacuated container carried by said insulated terminal, said container having a lower flexible metal wall, stationary and movable contact members disposed within said container, said stationary contact member having an electrical connection with said terminal, said movable contact memberhaving an operative connection with said flexible metal wall, and a switch operating rod disposed externally of said container and having an operative connection with said flexible wall.

2. A circuit interrupter comprisng a pair of rigidly supported insulated terminals, an

evacuated container carried by the lower end of each terminal, each container having an upper wall composed of insulating material and a flexible lower wall which is sealed to said insulating upper wall in a vacuum-tight manner, stationary and movable contact members contained within said containers, said stationary contact members having electrical connections with said terminals, said movable contact members having electrical and 0 erative mechanical connections with said exible walls, a bar connecting said flexible walls, and operating mechanism connected with said bar.

3. A circuit interrupter comprising a pair of rigidly supported insulated termnals, an evacuated container carried by the lower end of each terminal, each container having an upper wall composed of insulating material and a flexible lower wall which is welded to said insulating upper wall in a vacuum-tight manner, stationary and movable contact members contained within said containers,

said stationary contact members having elec- 1 trical connections with said terminals, said movable contact members having electrical and operative mechanical connections with said flexible. walls, an operating bar connecting said flexigle walls, and means to contain an-insulating-fluidubody in which the aforesaid elements are immersed.

' 4. A circuit interrupter comprising an evacuated container having a flexible wall, stationary and movable contact members disposed within the container, and direction changing mechanism operatively connecting said movable contact member with said flexible wall whereby movement of said flexible wall in one direction effects the movementeof said movable contact member in the opposite direction;

5.- A circuit interrupter comprisin an evacuated container having a flexible wa 1 exposed to the vacuum of said container and also to the atmosphere and biased for move- 'ment inwardly of said container by atmos- "-=pheric pressure, an operating member connected externally with said wall, and engage able, and disengageable contact members in 'sai'd" container operated by said flexible wall and having means whereby movement of said flexible wall inwardly of said container efkf)ects the disengagement of said contact memers;

' 6. A circuit interrupter comprising an evacuated container ex osed to the vacuum of said container and also to the atmosphere and biased for movementinwardly of said container by atmospheric pressure having a movable operating element provided with a vacuum-tight connection with said container, an operating member located externally of said container for operating said operating element, and engageable and disengageable contact members in said container operated by said operating element and having means whereby movement of said operating element inwardly of said container efl'ects the disengagement of said contact members.

7. A circuit interrupter comprising an evacuated receptacle having an interrupteroperating member which is exposed to the vacuum of said receptacle and also to the atmosphere and is biased for movement into said receptacle by atmospheric pressure, and engageable and disengageable contact members in said receptacle operated by said operatin member and having war movement of sai operating member effects the disengagement of said contact means whereby in- 

